After much wait, I have finely put a prototype together and put it to the test.To recap; the goal was to create a way to lower the throat opening of a FGM wood fired oven raised dome, to obtain the 63% dome to opening ratio.The throat reducer is made of 2" thick vermiculite and Portland cement mix. The piece was cut right at a height of 7"3/4, for a dome at 12"1/2, I let you do the math. I tried on my 700 C raised which is the smallest oven from FGM.

The down sides:- First issue, the throat being lower than the door opening, the smoke was escaping out through the door and not the chimney ... pretty nasty. I was kind of expecting it as the owner of FGM told me it would happen.I hastily put together a system to lower the door opening. Not very eye pleasing but worked quite well.- Second issue, the opening being reduced in width, it was harder to put the pizza in using my regular peel. I knocked the piece off a couple of time and it didn't miss to break it on one side. This issue will be alleviated when I get the throat reduce made out of metal on Tuesday.- Third issue and the most impotent one, the opening was reduced in height. I couldn't see as well in the oven which was a problem from putting the wood in, controlling the fire and cooking the pizza. My oven floor is at 51" and a higher floor would make it tiring for the arm.

The oven took about the same time to heat up, about 2 hours, with the same amount of wood to get it where I wanted it to be, 900F.

The positive side:- First good aspect, I only kept a smaller flame, similar to the regular height dome, to get a nice top on the pizza. Almost burned a couple and had to adjust my technique a little.- Second, the oven was easier to keep at such high temperature, therefore resulting in using a little less wood. I cooked 6 pizza in less than 10 minutes, could have done better if my wife had kept the pace - Third the hot air pocket created helped a lot to color the pizza when I raised it to the top.

I should get the fabricated metal piece form the master welder on Tuesday and will be able to try it out by next weekend. Then I will make it available to Reep so he can give his unbiased opinion while trying on a larger oven.

Conclusion after a first try, not much of a difference in heat-up time. Was easier to keep at temperature and nice pizza top.

Most importantly, the family loved the pizza as usual and I barely was able to take a picture of a pizza out of the 6 I cooked

Thanks Antoine. It seems like you should be able to use thin metal strips (1" front to back, 1/4" thick side to side) below the 63% mark to widen the opening. I'm not sure I will be able to provide enough expert testing. I may need one of the gurus on this site to come over and give me a lesson and test at the same time.

My guess is that if you really watch it, it could be a slight improvement (lower door), but will require a lot more babysitting to make sure you can get it out the lower door without dropping it. I think the biggest test for me is to see if it is worth the hassle of working in the smaller door space. If both produce the same looking pizzas, the bigger door would make things easier.

scott123

That is stunning. I am incredibly impressed. You just made a lot of trees happy. Your throat reducer has me all choked up

Less wood, faster pre-heats, faster bakes, better pizza. My hemming and hawing are officially over. FGM has my unequivocal endorsement. Feel free to use any of these statements in your promotional materials

One tiny nit The NY folks would probably like a little less protrusion near the floor, to allow larger peels/pizzas to clear. In a perfect world, the throat mods could be suspended with zero loss of lateral clearance near the floor, but that's not feasible. A little less metal would be nice, though, if it's possible.

I can't quite tell how it sits in place. How permanent is it? No mortar, correct? Is the inner door relatively air tight?

scott123

Thank you Scott for the kind comments.Wait, you said no more "hemming and hawing", just a couple of line and it is already over?

Antoine, I can be Team FGM's biggest cheerleader and still make suggestions, right?

When I talk about less metal, it's not relating to a thinner gauge. You're gauge selection is absolutely perfect for this temp- as you said, just thick enough not to warp. It's hard to explain the mod I'm looking for. I'm hoping for smaller legs- leaving the arc the same at the top, but cutting out a wider swath near the floor so the clearance towards the bottom increases for larger peels, and larger NY style pies.

But, as you said, let's not jump the gun. Is Reep the official beta tester on this?

Btw, for everyone that participated in the previous thread, when this trims more than 25% off wood consumption and pre-heat times, expect plenty of gloating. Look for me, in the end zone, doing a dance and spiking the ball

Alright everyone I have had 4 throat reducer prototypes made, kept one for my self and sent the 3 others to forum members who agreed to test them out. One of them is Reep, no news there, but the 2 others will have to introduce themselves Any how, let the experiment begin and I look forward to the results.

“Fabricate an insert, and pre-heat the oven with and without it. If the insert doesn't trim off at least 1/4 of the pre-heat time (and use at least 1/4 less wood to reach the same temps), I'll eat my hat”

Well, it is way too early to set the table for a hat feast, but the kitchen staff may be cooking it up.

Given that Antoine invited us to report out, I will share my limited experience so far.

I have the FGM 700, with the higher dome, door. I picked it for the versatility (not sure yet if that was necessary but I hope to have this for years to come) of fitting anything in there, regardless of height.

I have been a bit frustrated with achieving high temperatures, in terms of wood and time, as well as top heat. Top heat, as an issue, seems to be real but minor. A little bit of doming seems to take care of things. And, in researching many threads, that does not seem at all unusual.

In terms of time/temperature to reach Neapolitan levels, it does take a long time and a lot of wood. I know the oven is well insulated and the mass adds time. Antoine and I have had an ongoing conversation about this and he has provided great coaching/feedback.

He is convinced that I will get better results by using a different wood, e.g. well seasoned oak. I am using almond wood and it is, supposedly, well seasoned. I do get hissing in burning some logs and I do get significant smoke for perhaps 30 minutes or so when starting. I get major amounts of coals as the wood burns. But, it is what it is, I have at least 2 months to go with this wood.

In terms of comparison testing, I do not think it matters, since I am testing the oven with and without the insert. Obviously, it is good to maintain consistency in all other conditions.

I have only one “paired sample”, so right now n=1. That is why I am sure it is not hat meal time, at least yet.

But, this initial result was not encouraging.

2 weekends ago, I decided to try to minimize heat up time and not worry at all about wood consumption. So, I stuffed the oven with wood and kept stuffing it to keep a big fire going at all times. I was actually not making pizza that day, I was making some eggplant parmesan. So, I stopped a bit early before achieving very high neapolitan temperatures.

Last weekend, I tried to follow the same process with the insert (having just received it). I did not duplicate everything exactly – I did not weigh and count sticks of wood and time when they were placed in the oven. And the first time was a windier and cooler day than the second. But, with those caveats and more, I followed the same approach and here is the comparison (temperature is degrees Celsius using the FGM thermometer)

Comparing my results after 2:30 (after that, the comparison cannot be made since I stopped adding one in one of the heat ups), the results are identical! The heat up curves do seem to be bit different.

I also can observe that the throat reducer gave a clear advantage in terms of smoke. With it, all of the startup smoke went up the chimney. Without it, I get a lot coming out the front for the first.

The pizza picture is from the session using the insert. Baked in 1:28 including doming. The cheese was whatever was sitting around in the house with some cut up tomatoes. The oven picture is the coal bed when I stopped adding wood.

My hope is that Scott save his appetite for pizza since I really want the new gizmo to make a difference!

MitchAs someone who is seriously considering a BreadStone Oven, I am following this thread closelyWhile I realize the "testing" is just starting. However I want to take a moment to thank you for the well thought out and obviously time consuming effort you put into your first comparison firing.Obviously a rigid adherence to Scientific Method will be limited as you point out by uncontrollable variables. However a gestalt impressions hopefully will be obtainableGives me new faith in the value of messageboardsMichael

Just to clarify for everyone, the FGM thermometer measures the temperature 2" inside the thickness ( out if 3"1/4 ) of the dome wall. This results in accurately measuring the sustainable temperature of the oven rather than the cooking chamber or surface temp when using a door mounted or IR thermometer.

I do have my throat reducer now, but unfortunately my dome assembly has been delayed. I'm going to use my contractor's guys to do the heavy lifting and they are delayed. Hopefully get assembly done in the next couple of weeks.

scott123

Just to clarify for everyone, the FGM thermometer measures the temperature 2" inside the thickness ( out if 3"1/4 ) of the dome wall.

It can take a long time for heat to penetrate 2" of firebrick. Because of the insulating nature of the brick, it may delay the impact of the reduced throat. I know I'm asking a lot, but I'd like to see some dome temps, and, if not dome, then the same spot on the back wall.

It can take a long time for heat to penetrate 2" of firebrick. Because of the insulating nature of the brick, it may delay the impact of the reduced throat. I know I'm asking a lot, but I'd like to see some dome temps, and, if not dome, then the same spot on the back wall.

The bricks do not insulate, they actually absorb the heat about 20% faster that refractory concrete. Keep in mind those are not your average bricks like what you find in a fire place.

Mitch has a 700 concrete dome, Reep has a 1500 Short brick dome and the third one is a 950 bricked dome, testing will tell.

Throat reducer or not, I can get the surface temp to 800 or 900 F in 30 to 45 minutes and cook a couple of pizza. The problem is that it is only surface temp and after a couple of pizza the heat has dropped dramatically.As John has experienced with the 950 B if you heat up the oven to core temperature then you can cook pizza endlessly.